1. Field of the Invention
The present invention relates to a shield plate, an apparatus equipped with this shield plate, an electronic appliance assembled with this shield plate in an integral body, and a remote control system for such an electronic appliance equipped with this shield plate. More specifically, the shield plate of the present invention has an improved structure in order that when there are provided a plurality of electronic appliances including such communication means using radio signals within the same frequency band, for example, infrared communication signals, one communication signal used between specific electronic appliances does not interfere with the communication signals of other electronic appliances.
2. Description of the Related Art
FIG. 12 schematically represents one conventional remote control system 1 arranged by a plurality of electronic appliances equipped with the communication means for transmitting/receiving the radio signals having the frequencies in the same frequency band, for instance, infrared communication signals. This remote control system 1 is constructed of a television receiver main body 2 equipped with the infrared light receiving unit, the VCR 3, the cable box 4, the cable box controller 5, and the remote control apparatus 6. The television receiver main body 2 displays not only the TV picture of the specific TV channel selected from the TV signals received from the antenna 7, but also the cable TV picture derived from the cable 8 for the cable television.
The cable box controller 5 transmits the signal in the infrared form produced based on a predetermined format from the television receiver main body 2, and has such a structure equipped with the infrared light emitting unit 10. This cable box controller 5 is connected via the communication signal cable for transmitting the infrared code to the output terminal of the television receiver main body 2.
The cable 8 for the cable television receiver is connected to the cable box 4, and the infrared light receiving unit 9 at a preselected position of this cable box 4.
On the other hand, the antenna 7 is connected to the VCR 3, and the picture (video) cable from this VCR 3 is connected to the input terminal of the television receiver main body 2.
In the remote control system 1 for the electronic appliance with the above-described arrangement, for instance, when the remote control apparatus 6 is operated with reference to the character information and the like displayed on the television receiver main body 2, the infrared communication signals 12a and 12b are received by the infrared light receiving unit 11 provided on the side of the television receiver main body 2, so that either a predetermined picture is displayed, or such an infrared communication signal 12c is transmitted to the cable box 4, thereby displaying the picture of the designated cable television, when the cable television is designated. This infrared communication signal 12c is transmitted from the output terminal to the cable box controller 5, and has been converted into the signal cable of controlling the cable box 4 from this cable box controller 5.
However, the above-explained conventional remote control system owns such a problem that the infrared coded signal derived from the remote control apparatus 6 may interfere with the communication signal in the infrared form derived from the cable box controller 5 utilized in the cable television receiver, resulting in interference conditions.
This interference problem could be solved by the prior art system as described in Japanese Laid-open Patent Application No. 2-2225 opened in 1990. The structure of this conventional system is schematically shown in FIG. 13. That is, in order to avoid such a problem that when the infrared rays of the plural remoter controllers may interfere with each other, the operation of the own unit cannot be performed, the spectroscopes 31A, 31B and the slit plates 32A, 32B are positioned in the light receiving unit 30.
There is another prior art system as disclosed in Japanese Laid-open Patent Application No. 6-112664 opened in 1994. The construction of this prior art system is shown in FIG. 14 and FIG. 15. That is, in order to avoid that the remote control signal emitted from the inside of the AV rack 33 interferes with the externally incoming remote control signal, the door 34 of the AV rack 33 is made of the material capable of reflecting the infrared remote control signal so as not to externally enter the remote control signal. This infrared reflecting structure is made by, for instance, the infrared shielding film 35, the glass 36, and the magic mirror 37.
Further, the control system arranged by the infrared transmitting/receiving unit having a plurality of light receiving units, and by a plurality of electronic appliances connected to this infrared transmitting/receiving unit is known from U.S. Pat. No. 4,897,883 and U.S. Pat. No. 4,864,647.
However, even when the above-described improved prior art system is employed, the physical positional relationship between the electronic appliances using the infrared communication signals should be taken into account in order that, for instance, the infrared communication signal used between the remote control unit and the cable box controller does not interfere with the infrared communication signals used in other electronic appliances. In other words, there is such a problem with respect to the operations of the remote control unit, that the operability and the operating range of the remote control unit employed in the conventional - - - system are greatly restricted.
As a consequence, when a plurality of electronic appliances equipped with, for example, the infrared communication means operable in the same frequency range are provided in the system, this system must avoid such a problem that the infrared communication signals used among these electronic appliances will interfere with each other by employing a simple arrangement.